A gas turbine includes a compressor, a combustor and a turbine. A working fluid (e.g., air) flows into the compressor where it is progressively compressed as it is routed towards the combustor. At least a portion of the compressed working fluid is mixed with a fuel such as natural gas to provide a combustible mixture to a combustion chamber defined within the combustor where it is burned to generate combustion gases having a high temperature and pressure. The combustion gases are routed into the turbine. Thermal and kinetic energy is transferred from the combustion gases to successive stages of rotor blades that are coupled to a rotor shaft, thereby causing the shaft to rotate and produce work. For example, the shaft may drive a generator to produce electricity.
Rotor blades typically include a mounting portion and an airfoil portion that extends radially outwardly from the mounting portion. The mounting portion may include a dovetail feature for securing the rotor blade to the rotor shaft. The airfoil portion generally includes an airfoil body which defines a leading edge, a trialing edge, a pressure side and a suction side where the pressure and suction sides intersect at the leading and trailing edges. The leading edge generally faces towards the flow of combustion gases and the pressure side is configured to receive the combustion gases and extract kinetic energy thereform.
High combustion gas temperatures within the turbine section generally corresponds to greater thermal and kinetic energy transfer between the combustion gases and the rotor blades, thereby enhancing overall power output of the gas turbine. However, overtime high combustion gas temperatures may lead to erosion, creep, and/or low cycle fatigue to the rotor blades, particularly at a radially outward portion of the trailing edge of the airfoil body, thereby potentially limiting durability of the rotor blades. Therefore, continued improvements in rotor blade cooling are useful.